Should You Add Acoustic Material Behind In-Wall and In-Ceiling Speakers
Installing in-wall and in-ceiling speakers can be scary. Once they are in, they are in. There is no moving them. Therefore, you very much want to get it right the first time. Now that you’ve decided on placement and you’ve got your holes cut, you are looking at that big, empty cavity inside your wall. You are about to install that speaker and it doesn’t seem right to leave that area empty. Should you add acoustic material behind in-wall and in-ceiling speakers? Let’s discuss!
Generally Speaking – Yes
In home theater, if your question is about adding acoustic material anywhere in your room (even inside the walls and ceilings behind your in-wall and in-ceiling speakers), the answer is “Yes.” For in-ceiling speakers, this is less of an issue. Most in-ceiling speakers have insulation already in the area above them (attics). In multistory homes, however, this might not be the case. So, let’s look at specific types of speakers.
Speakers with Backer Boxes
We recommend that you either buy speakers with integrated backer boxes or build your own. Always. It is often code (especially for in-ceiling speakers), but it is better sonically. Since you have that backer box, do you need additional acoustic material? We’d argue that you do.
Most backer boxes are rigid. This keeps the air volume inside contained, but the box will also vibrate. While the backer box will contain some of the sound, it will not contain all of it. Surrounding the speaker in acoustic material will reduce the amount of sound that is leaked from the speaker into your wall or ceiling from your in-ceiling or in-wall speakers. It costs very little and can provide pretty significant benefits.
Speakers without Backer Boxes
Again, if your in-wall or in-ceiling speaker doesn’t come with a backer box, you should either buy an aftermarket one or build your own. If you decide not to enclose the back of your speaker, then adding acoustic material is even more important. The inside of your wall or ceiling, if it has no acoustic material, will transmit the sound from the speaker easily. Remember, in an open-back speaker, nearly as much sound is traveling into your wall/ceiling/attic as into your room! Adding acoustic material will help reduce the volume that is transmitted into your walls/ceiling and to the rest of your home.
Adding acoustic material to your home theater is nearly always a good thing. If you are opening up walls or ceilings for speakers, it makes sense to take a little extra time and expense to add some acoustic material. It will make your speakers sound better, it will reduce sound transmission to other rooms, and it will give you peace of mind that you installed your speakers correctly. All for not a lot of time or expense.